The invention relates to a chain link conveyor comprising a number of identical chain links of plastic with eye-shaped hinge parts in the edge of opposite sides and arranged to be coupled together with corresponding hinge parts in neighboring chain links by means of a common pin or axle through the openings in the hinge parts, with the hinge parts on the opposite sides of each chain link being mutually displaced, opposite hinge parts in each chain link being coupled together by ribs or connecting parts, and with transverse parts arranged to engage with a driving wheel, which transverse parts are integral with the ribs or connecting parts.
Chain links of this type for chain link conveyors are usually made of plastic by injection moulding in a suitable plastic material depending on use etc., as each link is moulded as an integral unit, which by axles or pins, either steel or plastic axles, are assembled to an endless conveyor chain to be pulled by one or more chain wheels and led over one or more idle wheels. Such modular chain links may also be assembled width-wise to form wide conveyor belts.
Chain links of this type are for example, proposed in U.S. Pat. No. 4,832,187, wherein a transverse row of central openings is arranged to engage with chain wheels for conveyance in any direction. In addition to this, the chain link comprises a number of eye-shaped hinge parts for engagement with neighbouring chain links. All the parts have a narrow but plane, upwardly facing edge, which edges together constitute a top surface arranged to carry the material to be conveyed.
U.S. Pat. No. 4,051,949 proposes another type of chain link for a chain link conveyor or a conveyor belt, viz. a chain link with upwardly extending ribs, the plane top edges of which constitute the top surface which is arranged to carry the material to be conveyed.
Chain links of the above-mentioned types are often used in chain link conveyors or chain link belts for cans, for example aluminium cans for beverages such as beer, coke etc., or for the reusable large bottles of plastic, which are very popular at present, which bottles are used for coke and other soft drinks in particular. As an example, the chain link belts can be used in the supply of empty containers to a filling machine and in the further transport to a packing and casing department etc. In this connection various problems have often been observed. Aluminium cans leave a thin layer of aluminium oxide on the top surface of the conveyor resulting in a great and constant need for cleaning, a cleaning which is a demanding task, because aluminium oxide sticks extremely firmly to many of the types of plastic which for other reasons are used for the production of chain links.
The openings in the top surface present another problem. These openings cause the reusable large bottles of plastic to stand in an unstable manner, because their bottom is configured with five support points. These bottles are often referred to as petaloid bottles.
The friction between the items, be it aluminium cans or petaloid bottles, and the surface of the chain link belt presents a third problem when the empty items are being stowed, for example, in front of the filling machine. If the friction is too high, which is possible with the conveyor belts of the known types, the items at the front may be deformed, which is not acceptable. Aluminium smudging can cause varying friction and unstable conveyance.
The company often demands that the belts be operated without lubrication, so-called dry conveyance, which also increases the friction between the conveyor belt and the items placed on it. A too high friction can also be due to poor cleaning or sticky material which has been spilt on the belt, for example coke, beer etc.
Finally, it is a purely practical experience that chain links with freely upward extending ribs have a tendency to cause pulsations in the belt and as a consequence, uneven conveyance, which is not desirable.